Method of Decreasing Sheet Resistance in an Article Coated with a Transparent Conductive Oxide

Abstract

The invention is methods of reducing a sheet resistance or changing emissivity of a coated article. A coating is applied over a substrate wherein that contains a transparent conductive oxide layer at room temperature. The transparent conductive oxide layer is processed by generating an Eddy current in the transparent conductive oxide, flash annealing the transparent conductive oxide layer so that the transparent conductive oxide layer reaches a temperature of above 380° F., or heating the coated article such that the transparent conductive oxide layer is heated to above 380° F.

1 . A method of reducing a sheet resistance of a coated article comprising applying a coating to a substrate wherein the coating comprises a transparent conductive oxide layer at room temperature; and processing the transparent conductive oxide layer wherein the processing step is selected from the group consisting of (a) generating an Eddy current in the transparent conductive oxide, (b) flash annealing the transparent conductive oxide layer so that the transparent conductive oxide layer reaches a temperature of above 380° F., (c) heating the coated articlesuch that the transparent conductive oxide layer is heated to above 380° F. 
     
     
         2 . The method according to  claim 1  wherein the processing step is (c) heating the coated article. 
     
     
         3 . The method according to  claim 1  wherein the transparent conductive oxide layer is at least 125 nm and at most nm to 950 nm. 
     
     
         4 . The method according to  claim 1  wherein the transparent conductive oxide layer comprises tin-doped indium oxide and is at least 105 nm and at most 171 nm, and wherein the sheet resistance of the coated article after the processing step is less than 20 Ω/□. 
     
     
         5 . The method according to  claim 1 , wherein the transparent conductive oxide layer comprises gallium-doped zinc oxide having a thickness of at least 320 nm and at most 480 nm and wherein the sheet resistance of the coated article after the processing step is less than 20 Ω/□. 
     
     
         6 . The method according to  claim 1 , wherein the transparent conductive oxide layer comprises alumina-doped oxide having a thickness of at least 344 nm and at most 880 nm, and wherein the sheet resistance of the coated article after the processing step is less than 20 Ω/□. 
     
     
         7 . The method according to  claim 1 , wherein the applying the coating step comprises a magnetron sputtered vacuum deposition process. 
     
     
         8 . The method according to  claim 2  wherein the transparent conductive oxide is heat at least to 435° F. 
     
     
         9 . The method according to  claim 1  further comprising applying a first protective film over at least a portion transparent conductive oxide layer, wherein the first protective film comprise titania, alumina, zinc oxide, tin oxide, zirconia, silica or mixtures thereof, and applying a second protective film over at least a portion of the transparent conductive oxide layer wherein the second protective film comprises titania and alumina, and wherein the applying the first protective film and applying the second protective film occurs before or after the processing step. 
     
     
         10 . The method according to  claim 1  wherein the heating step does not raise the top surface of the transparent conductive oxide above 635° F. 
     
     
         11 . The method according to  claim 1  wherein the substrate is glass and the transparent conductive oxide has an absorption not greater than 0.3. 
     
     
         12 . The method according to  claim 1  wherein the substrate is glass and the transparent conductive oxide has an absorption at least as high as 0.05. 
     
     
         13 . The method according to  claim 1 , wherein the coated article is a refrigerator door. 
     
     
         14 . The method according to  claim 1 , wherein the applying step is done in an atmosphere that has an oxygen content supplied to the atmosphere of between 0% and 1.5%. 
     
     
         15 . The method according to  claim 1  wherein the substrate is glass and the transparent conductive oxide has an absorption not greater than 0.2 and at least as high as 0.05. 
     
     
         16 . A method of making a coated article comprising the steps of applying a transparent conductive oxide layer over a substrate, raising a top surface of the transparent conductive oxide to above 380° F. and not raising the top surface of the transparent conductive oxide above 806° F. 
     
     
         17 . The method according to  claim 16  further comprising not heating the coated article above 635° F. 
     
     
         18 . The method according to  claim 16  wherein the transparent conductive oxide layer comprises tin-doped indium oxide having a thickness of at least 96 nm and at most 171 nm and a sheet resistance of less than 25 Ω/□. 
     
     
         19 . The method according to  claim 16  further comprising applying a protective layer over the transparent conductive oxide wherein the protective layer comprises titania and alumina. 
     
     
         20 . A coated article having decrease sheet resistance made by a process comprising applying a coating to a substrate wherein the coating comprises a transparent conductive oxide layer at room temperature; and processing the transparent conductive oxide layer wherein the processing step is selected from the group consisting of (a) generating an Eddy current in the transparent conductive oxide, (b) flash annealing the transparent conductive oxide layer so that the transparent conductive oxide layer reaches a temperature of above 380° F., (c) heating the coated articlesuch that the transparent conductive oxide layer is heated to above 380° F.